Advanced skaters demand more from a skate boot due to superior skills and maneuverability, the requirement for quick turns and stops, and increased power and strength which increases an ability to flex limbs through a greater range of motion. This requires a skate boot which provides support and a dynamic range of motion.
The biomechanics describing the movement of an unrestrained foot and leg are more dynamic than the limited movements permitted by a traditional skate boots. Currently hockey and inline skates are designed primarily to provide ankle support, using one piece uppers of varying stiffness, with ankle-covering side panels that extend from a skate's achilles tendon guard and the lower boot below. These side panels are usually tightened with lacing in the upper sections of the boot. However, because the lacing eyelets are fixed to the rigidly mounted side panels and tendon guard which are not designed to bend, today's hockey skates are incapable of properly flexing forward or backward when providing full ankle support.
Because the continuous execution of more extreme biomechanical movements exceeds the restricted range of motion provided by traditional skate boot constructions, such skating actions pinch the muscles and tendons in front of the ankle, and chafe the skin and bone of the heel, especially when skate boot laces are tied tightly.
To be effective, skate boot constructions for ice skating or inline roller skating should address the mechanics of skating as well as the anatomical features of the foot, ankle, and lower shin. However traditional skate boot designs have not changed much since they were first invented about 100 years ago. Traditional skate boots utilize a composite one-piece upper which surrounds and supports the ankle, but, in doing so, does not allow for full ankle movement.
Such constructions only allow limited movement, depending on the deflection and flexibility characteristics of the construction materials used. All construction materials have defined yield points that limit how far the material's structure can be strained before it permanently bends, creases, or is distorted in some other manner. Today's more dynamic skating movements exceed the flexibility yield points of rigid skate boot materials, causing a rapid breakdown in the materials making up the side walls of conventional skate boots.
As cited in research on the influence of skate boot design on ankle biomechanics, done by Hancock, Lamontagne, Stothart and Sveistrup at the University of Ottawa, “a decrease in range of motion corresponded to an increase in elastic joint moment and an increase in joint stiffness. If this joint restriction is excessive, a skater will have to adapt with a change in skating technique that may create undue fatigue or a decrease in skating efficiency. These findings suggest that the design and construction of a hockey skate boot has a definite influence on the functioning of the ankle joint complex, and skate manufacturers should consider these factors when designing for optimal skating performance.” (Cited from S. Hancock, M. Lamontagne, J. P. Stothart and H. Sveistrup THE INFLUENCE OF THREE HOCKEY SKATE BOOTS ON THE RANGE OF MOTION, ELASTIC MOMENT AND STIFFNESS OF THE HUMAN ANKLE JOINT COMPLEX, Presented to the International Society of Biomechanics Congress XVII, Calgary, Canada, 1999, which is hereby incorporated by reference). Empirical testing of conventional hockey skate boots confirms this hypothesis.
A modern skate boot typically consists of a high boot and sole which are stiff. The sole is connected to the skate blade sheath or inline roller mechanism. The boot is typically tied with laces through eyelets in the front of the boot. There may be from eight to thirteen pairs of matching eyelets mounted on a typical skate boot. Yet many power skaters only lace a portion of these eyelets, normally starting at the bottom and terminating before the top eyelets are laced, or leaving these top eyelets more loosely fastened. This indicates a problem in the design of conventional skate boots.
Because the base of the foot is several inches above the skating surface, strength must be built into the sides of the boot to provide the stability and control required for turning and stopping. However at times the skater requires flexibility in movement of the foot in the four primary directions: down (plantar flexion), up (dorsiflexion), and laterally right or left (inversion/eversion) about the ankle pivot.
Prior art skate boots significantly restrict the dorsiflexion of the foot. Product testing of such prior art's ability to dorsiflex has shown this to be less than fifteen degrees. This is significantly less than a range of motion achieved through dorsiflexion of the foot. For example, ankle dorsiflexion rotation angles measured on test subjects while running reached a maximum of 30 degrees (cited from Novacheck, T. F. M.D., THE BIOMECHANICS OF RUNNING, Gate and Posture, 7, 1998, which is hereby incorporated by reference).
The leg and ankle allow the foot to dorsiflex or plantarflex by contracting and relaxing muscles attached to the lower leg. Dorsiflexion, necessary for forward leaning flexion of the lower leg over the ankle, is achieved by contracting shin muscles on the front of the leg, and relaxing calf muscles on the back of the leg. The relaxing calf muscles allow a lengthening of the distance between the knee and heel. This allows the tibia to lean forward when skating.
The contraction of muscles on the front of the leg and foot causes a shortening of the distance between the top of the instep and the lower shin on the front side of the ankle. This contraction causes a normal expansion, or swelling, of the muscles and tendons in the front of the ankle. Anything that restricts either of these two movements will impede dorsiflexion of the foot.
Therefore a successful skate design must: allow the tibia to lean forward while providing ankle support, and allow for swelling of muscles and tendons in front of the ankle, just above the instep of the foot. Skate designs, such as most prior art skates, that do not allow advanced skaters to achieve such movement cause irritation and sometimes permanent injury to the skater.
The most serious of these injuries involves the development of heel spurs after intensive use of a restrictive skate boot. At the middle of the skating push phase the foot and skate are in a fully dorsiflexed position. In a conventional skate boot the laces stretch slightly. However, the upper lacing on traditional skate boots is attached to a rigid tendon guard which does not allow it, or the attached lacing, to stretch and travel with a leg that it leaning forward as a dorsiflexion of the foot is performed. The rigidly fixed top row of eyelets of a traditional lacing system ultimately becomes a lifting fulcrum in front of the lower shin once it is initially flexed forward.
If the skater continues to flex forward, the upper portion of the shin, which is now leaned over and against this lacing barrier, forces the lower shin and heel to rotate about the fulcrum caused by the rigid lacing system. The resulting action, a rotation about this fulcrum, causes the heel at the bottom end of the lever to lift upwards and backwards, jamming the heel against the heel support in the skate boot, in turn causing blistering to the heel in the short term. Because the skin and fatty padding beneath the skin of the heel (and achilles tendon) are stretched to their limit at full dorsiflexion, protection from chaffing and shock are reduced, enhancing the potential for large heel spurs over the longer term.
A second cause of irritation on the front of the ankle region, called “lace-bite”, is also due to resistance to forward flexion of the leg over the front of the skate's upper lacing system at more extreme angles of dorsiflexion, again during mid stride of the push phase of skating.
“Lace-bite” on the front of the ankle, specifically on the extrinsic extensor hallucis longus muscle and tendon, is caused by skating with tightened upper laces and eyelets that are attached to a rigid tendon guard. This extensor, located on the center to inside front of the foot, connects the large toe bones to the leg.
As described above, when tensed in dorsiflexion, despite being restricted by facial ligaments (superior extensor retinaculum and inferior extensor retinaculum) this tendon's surface profile rises ¼-½ inch above the relaxed surface profile of the front of the foot in a neutral position. The extensor digitorum longus muscle and tendon is on the outside front of the foot and connects to the smaller toes. It also lifts and expands a smaller amount in dorsiflexion. This natural swelling of the ankle further increases pressure against the rigidly mounted lacing system, which is already causing pressure from resisting the action of the forward leaning shin.
Prior art over the years has provided for a number of methods in an attempt to solve the problems described above. However none of these methods provide full ankle flexion in combination with rigid lateral ankle support that is required for aggressive play. This has either caused the patented design to fail entirely in real world testing, or has produced skate boots with limited movement resulting in unnecessary pressure and friction on various parts of the foot and leg when skating powerfully.
In U.S. Pat. No. 6,550,159 issued to Madore on Apr. 22, 2003 and in Canadian Patent Application No. 2,309,565 filed in the name of Madore and published on Nov. 25, 2001, which are hereby incorporated by reference, a skate boot which comprising an articulated cuff for encircling and supporting the ankle of a skater is described. The articulated cuff is partially inserted in the foot element and slidably coupled to the foot element to permit unrestrained limited pivotal motion of the articulated cuff relative to an axis coinciding approximately with the pivot axis of the skater's ankle.
However the design of this skate is problematic for several reasons. First the ankle's axis of rotation relative to the foot is a few inches above the resting plane of the foot itself. As with any such axis point, any radial member attached above the axis will rotate in one direction, and anything below will rotate in the opposite direction. This means that as the cuff positioned above the ankle's rotation axis is rotated forward (with the shin that is flexing forward), any structural attachment extending below this point (to be anchored to the foot below) will rotate backwards at the same time. This backward motion must be shielded from the foot itself which is not moving, otherwise it will chafe the foot. This would require a “slidable track” described in the patent to be buried in the side of the boot under a stationary piece of material which would rest against the foot. The track would also increase the width of the heel, and weight of the boot. In addition, such a track would describe an arc proportional to the distance of the track from the fixed position of the ankle's axis of rotation. This is problematic as it requires a fixing of the athlete's ankle position, and this ankle position is different in every athlete.
More problematic, the range of motion required for skating is limited by the design presented in these documents. The slidable track beneath the ankle is positioned forward to allow full plantar flexion. However this positioning leaves little room for backward movement of the cuffs track, necessary for forward flexion of the cuff under dorsiflexion. Furthermore, where as a traditional tendon guard is one continuous piece, this design requires a split boot, which when leaned forward will cause the tendon guard to gap open, creating the potential to get full of snow and wet. Obstructing matter could also get jammed in the opening as well, preventing the boot from returning to its closed upright position.
Madore and Wright's subsequent Canadian Patent Application No. 2,328,569 published on Oct. 28, 2001, which is hereby incorporated by reference, attempts to solve these problems by substituting the rigid side and tendon panels of a conventional skate, which eventually breakdown, with flexible molded side panels.
However successful hockey skates require rigid sidewalls to provide adequate ankle support required for aggressive play associated with hockey. Madore and Wright's foam side panels allow greater potential for dorsiflexion and plantar flexion than most conventional skates, but are very soft and do not provide rigid lateral support required by aggressive professional players.
Felice, in Canadian Patent Application No. 2,385,202, published Oct. 5, 2003, which is hereby incorporated by reference, describes the use of a flexible ankle encircling cuff made of synthetic moldable plastic material capable of flexing in the forward, aft, and lateral directions to act as an energy storage and release device and without wrinkling so as to minimize discomfort and abrasion on the user's ankle and extend the useful life of the boot. The tongue portion of the boot has a similar molded synthetic flexible panel separating the upper and lower sections of the tongue.
This skate only achieves dorsiflexion by collapsing and bunching in the front, rather than elongating and stretching in the rear as one's achilles tendon is designed. A bunching elastomer included in the design displaces increased volume at front of the ankle when collapsing to accommodate forward lean associated with dorsiflexion. This design further compounds crowding problems caused by tissue expansion on the front of the foot when in a dorsiflexed position. It also causes increased heal lift under dorsiflexion and does not improve a range of motion of the skate during plantar flexion.
Felice's flexible/collapsible “Stove pipe” tube, while different from Madore and Wright's skate describe in Canadian Pat. No. 2,328,569, still does not have any rigid lateral ankle support, and is capable of collapsing in any direction, not providing the lateral ankle stability required for hockey. Successful hockey skates require rigid sidewall support to provide adequate ankle support for aggressive play associated with hockey.
Schaeffer, in Canadian Patent 1,244,648, issued Nov. 15, 1988, and which is hereby incorporated by reference, describes a skate boot that allows very limited bending of a tendon guard, but not in amounts sufficient, and without the elongation required of power skaters generating more than 15 degrees of dorsiflexion.
The design also has the same flaw that causes all traditional skates to loose ankle support with age, as the side panels are not designed to deform and deflect under forward or backward flexion. While both the tendon guard on the back of this skate boot and the notched lacing systems on the front of this skate boot allow limited potential for forward flexion, the rigid one piece side panels connecting the latter and former do not. The only way such designs can flex forward or aft is if the side panel bends, which eventually causes a breakdown in skate boot support. This is the primary reason why skates wear out so quickly at the professional level.
U.S. Pat. No. 5,072,529 issued to Karl Graf on Dec. 17, 1991, and which is hereby incorporated by reference, describes a pivotable leg flap covering each ankle of a skate which moves with the ankle. The leg flap moving only in a laterally extended plane, not longitudinal, allowing increased lateral ability, but no additional forward motion of the tibia. The leg flap is provided with a second lacing region, which cooperates with a lower lacing region. This is to prevent the problem of the pad rubbing on the ankle and, because of the high surface pressure present, which often gives rise to irritation or even inflammation of the ankle section on the foot.
This skate doesn't solve the problems of irritation on the extensor hallucis longus, or the lack of flexibility in the tendon guard, which prevents the leg flap from fully pivoting as it should. The upper lacing attached to this flap causes heal lift under dorsiflexion as with all traditional skate designs. It also does nothing to improve plantar flexion, prevent tongue slip, or address the asymmetrical positions of the anklebones.
Linner and Linner in Canadian Pat. No. 2,212,229 published Aug. 15, 1996, and which is hereby incorporated by reference, teach of a complicated device in which a skate boot, shin pad, and other armored parts about the ankle are connected together, but that only move in one directional plane and don't allow any lateral rotation of the shin relative to the ankle. Eliminating the ability to laterally rotate the ankle, which is required by this design, would make advanced skating impossible. Moreover the design makes it impossible to secure the upper ankle properly. It's also too heavy and has many elastically loaded moving armor parts which are subject to lifting and jamming while in play.
The prior art of Olivieri in Canadian Patent No. 1,160,832, issued Jan. 24, 1984, Caporicci in Canadian Patent No. 1,066,500, issued Nov. 20, 1979, Mikhail in Canadian Patent No. 1,097,062, issued Mar. 10, 1981, and Bourque in Canadian Patent No. 1,046,271, issued Jan. 16, 1979, which are all hereby incorporated by reference, all teach of skates including various molded plastic skate boots with interior liners.
Several of the designs achieve full ankle mobility with different hinging ankle cuffs. However the hard plastic constructions required separate interior bladders or liners which deprive the skater of the fit and feel required for advanced performance. Such bladders are separate units which are slipped into the exterior plastic shell.
However, because they are designed as separate units, they are prone to slipping inside the shell. Such designs are adapted to skate design from the ski industry, where separate interior bladders do not affect a skier's performance as they affect a skater's. All such designs were subsequently passed over by professional players who achieved better performance in tightly fitting one-piece composite constructions of leather and synthetic leather lace-up constructions which are capable of custom forming to the foot of the individual athlete. No prior art has been able to achieve increased ankle mobility without a separate removable bladder. The skates described in these four patents also lack the additional lateral ankle support required by top hockey players.
None of the prior art cited hereinabove provides for a skate boot which is effective for the low hip, high dorsiflexion, power skating position of advanced skaters. The prior art either lacks flexibility, rigid lateral support, is too stiff, is too heavy, requires a separate bladder, is ineffective, or is too expensive to manufacture.
Against this background, there exists a need in the industry to provide a novel improved skate boot.